1. Field of the Invention
The invention relates to locating the position of a moving object. In particular, the present invention relates to acquiring, locating, and tracking single or multiple objects moving over a planar surface day or night regardless of weather conditions. More particularly, the invention relates to monitoring the movement or encroachment of an object onto an aircraft runway or taxiway.
2. Description of the Related Art
Tracking and locating aircraft and other moving vehicles on airport runways and taxiways is difficult when weather conditions are ideal. Tracking and guiding aircraft over runways and taxiways is usually accomplished by a flight controller visually sighting and visually tracking the taxiing aircraft, and directing the movement of the aircraft by voice commands to the aircraft from the flight controller. When weather conditions such as rain, snow, fog, smog, or dust obscure the flight controller's view of an airport's runways and taxiways, the airport is usually closed causing inconvenient and expensive delays to the airlines and passengers.
Systems for monitoring the movement of airplanes and other objects over the surface an airport runway or taxiway are known in the art. Exemplary of such systems are the following U.S. Patents:
U.S. Pat. No. 5,027,114 discloses a ground guidance system for airplanes in which loop coils of a predetermined shape are continuously buried in a specific section of a taxiway for airplanes, an airplane is continuously detected based on changes of self-inductances of the loop coils with movement of the airplane while discriminating airplanes from other objects and admission or inhibition of advance in the specific section to a subsequent airplane according to the presence or absence of the airplane in the specific section and which has a fail-safe structure not generating an output at the time of a system or circuit failure or accident.
U.S. Pat. No. 4,989,084 discloses a airport runway monitoring system which is for monitoring and recording the movement of aircraft and their external characteristics and paths during and after landing and take-off from an airport runway detects malfunctions, pilot error, equipment failure or other evidence that might assist in determining the cause of a crash or other malfunction. The system includes a plurality of video cameras located adjacent to the runway, a video recording device for saving information from the cameras, and a video transmission device connecting the cameras to the recording device.
U.S. Pat. No. 4,845,629 discloses an airport surveillance system which is a system for surveillance, guidance and fire fighting in airports. The system is arranged to monitor the position of aircraft in the taxiway, parking areas and flight lanes and in the event of an accident in the flight lane to extinguish any fires caused thereby. Infrared sensors are arranged along the flight lanes and their output signals are processed by a computer to provide information concerning the aircraft movements along the flight lanes. In the event of an emergency the computer processes the output signals from the sensors to determine the precise location and area of any heat sources in the flight lane and causes hydrants to direct fire-extinguishing fluid at the heat sources. Position detectors are provided for detecting the position of aircraft in the taxiway and parking areas. The output signals from the position detectors are processed by a computer to determine the position of the aircraft and the output of the computer is arranged successively to illuminated beacons to guide the aircraft along a selected route.
U.S. Pat. No. 4,418,349 discloses an airport surveillance system located adjacent to runways, taxiway, and approach ramps are secondary radar interrogators which radiate the P1 and P3 pulses and the P2 pulse via different directional patterns into sectors to be monitored which are individually assigned to each interrogator. Direction finders at different locations determine the directions of arrival of SSR reply signals radiated by an airborne SSR transponder in a sector to be monitored. From the directions of arrival and the locations of the direction finders, the respective transponder position is determined. The interrogators require no central control. Alternatively, the arrival times of the SSR reply signals are measured at several points; an evaluating device forms the differences in arrival time, and the intersection of the hyperbolic lines of position determined in the evaluating device is the position of the transponder.
U.S. Pat. No. 4,197,536 discloses an airport surface identification and control system for aircraft equipped with ATCRBS and ILS, an identification and surface guidance system including a plurality of detection positions each including an interrogator and an auxiliary transponder located adjacent the runway and on opposite sides thereof, respectively. The interrogator is enable through a signal cable from a remote location, such as a control tower, to produce the first of the discretely spaced pulse pair required to interrogate the ATCRBS equipment. The second interrogation pulse of the pair is generated by the transponder, which is activated by the radiated first pulse from the interrogator and includes an internal delay, such that this delay plus the transit time from the transponder serves to generate the second pulse of the pair if the aircraft to be interrogated is in the vicinity and on the pathway centerline or within a specified lateral tolerance therefrom. The ATCRBS reply may be received directly at the control tower or may be transmitted by cable from receiving equipment within the interrogator. ATCRBS decoding and display equipment may, be employed at the control tower for discrete identification of a give aircraft. The identification points are distributed along a runway, taxiway or other surface area of an airport for continuing identification. Time discrimination apparatus compares the ATCRBS pulse train received by the transponder and retransmitted therefrom to the interrogator to that received directly by the interrogator to generate a signal representative of the aircraft deviation from pathway centerline, and this signal is transmitted on an unused ILS channel to the aircraft for presentation to the pilot on the localizer cross pointer indicator within the aircraft.
U.S. Pat. No. 4,319,243 discloses an airport-surveillance system for determining the position and identification of aircraft (4) on the airfield which utilized secondary radar and includes an interrogation station (1) installed on the airfield (3) and from which the interrogation signal is transmitted by way of a narrow sharply focused beam of an antenna which scans the airfield and further includes transponding stations installed in the aircraft (4). The present invention provides accurate identification and location of the aircraft by utilizing a receiver which has a sharply focused antenna beam and which is geographically located a distance away from the interrogation antenna and wherein the replies from the transponder of the aircraft are received by the receiving antenna only when the interrogation and receiving antenna beams (2, 22) intersect. By scanning all locations of the airport, the position and identification of all aircraft on the airport can be determined. A modification of the invention provides that instead of or in addition to the receiving station having a narrow beam antenna a number of receivers (5,6 and 7) having amnii-directional receiving antennas can be mounted at different locations on the airfield for determining the aircraft positions by using hyperbola locating techniques. The airport surveillance system of the invention is particularly suitable for large airports.
U.S. Pat. No. 4,163,283 discloses an automatic method to identify aircraft types with two sensors spaced at a known separation produce signal pulses when activated by the wheels of a taxiing aircraft. The signals are transmitted to a processor in which the wheelbase of the aircraft can readily be calculated. Since specific aircraft types have unique wheelbase dimensions and characteristics, the type of aircraft passing the sensors is determined in a processor. Also, the time, direction, and speed of the aircraft can be determined and logged by the processor.
U.S. Pat. No. 4,151,595 discloses a system for controlling ground movements on runways and taxiway to be guided and a corresponding ground traffic to be controlled. The system includes sensors for detecting pressure variations and which are distributed at known intervals along the routes, each sensor having four linear arms arranged in pairs on both sides of the axis of the route in such a way that the items of data corresponding to the respective times at which the lateral wheels of the aircraft cross them enable, by means of a simple calculation performed by electronic processing of the detected signals, guidance and control instructions to be produced which include: heading deviation, speed together with its direction, and lateral deviation and in addition, instructions or orders such as changes of heading, changes of speed, emergency stops and runway turn offs.
U.S. Pat. No. 3,706,969 discloses an airport ground aircraft automatic taxi route selecting and traffic control system. As an identified object, such as an aircraft on the ground is scheduled to cross the surface traffic network of certain areas, such as an airport, its identification and point of destination on the ground are fed to an automatic digital computerized controller including integrated intersection traffic control and monitoring logic units, which automatically generates a selected route from the point of origin of the object to such destination point, and by appropriate guidance displays including such identification, directs the pilot or driver of the object at each traffic intersection when safely to enter and in which direction to proceed, until the object reaches the desired destination point.